This invention relates to dry wall joint compounds used to prepare dry wall joint cements and dry wall finishes.
When gypsum dry wall board or the like is used as a wall surfacing in construction projects, adhesive or cementitous fillers are usually used in combination with a tape material to close and fill the joints and corners between adjoining panels of the dry wall. Some of these fillers, and others with slightly modified formulations, are also used as finishes on dry wall surfaces.
In one widely used technique for filling dry wall joints, water is added to a gypsum joint filler compound to form a mud-like material which is applied with a trowel or the like to close the joint. A fiberglass, cloth or paper taping material is then stretched over the joint and embedded in the soft "mud". A overlayer or top dressing of the "mud" is applied over the taping material to completely fill the joint and provide a smooth surface. After setting, the top dressing usually must be sanded to smooth out irregularities prior to painting or applying a wall covering.
In addition to the multiple and time-consuming steps required for applying the tape and filler, many conventional wall board joint compounds have one or more of the following shortcomings: cannot be applied at sub-freezing temperatures, requires up to 24-48 hours to completely harden, shrinks to some degree upon drying, requires an additional top dressing to completely fill the joint unless some excess is applied, and is vulnerable to cracking, particularly when used on prefabricated or panelized modular wall or ceiling structures transported from an assembly plant to construction sites.